The present invention relates to an information recording and playback apparatus capable of recording information on a number of recording media and playing back recorded information, a content management method for use with the information recording and playback apparatus, and a content management program for use therewith.
In recent years, video recorders having two kinds of recording media, such as an HDD (Hard Disk Drive) and a writable optical disc such as a DVD (Digital Versatile Disc), have become popular. In such video recorders, different uses are made in such a manner that, for example, video content for the purpose of time shift viewing is recorded in an HDD, and video content for the purpose of a long period of storage is recorded on an optical disc.
Furthermore, recently, as an optical disc capable of recording a larger amount of data, a Blu-ray disc (hereinafter abbreviated as a “BD”) has been developed. The use of BDs makes it possible to record digital data of an HDTV (High Definition TeleVision) video provided by, for example, a digital broadcast which can be recorded for approximately two hours on one side of a BD.
As high-quality digital content can be easily stored in a portable recording medium in the manner described above, the importance of copyright protection of digital content has increased. In the video content at present, a method for attaching copy control information (CCI) indicating the permission/non-permission of copying to the data of content is generally used. For example, by using the copy control information, the data of each piece of video content can be made to be a state in which copying is not limited (copy free), a state in which copying is permitted only once (copy once), and a state in which copying is prohibited (copy never).
Among them, the video content that is recorded on a recording medium as a result of being set as copy once is permitted to be recorded on another recording medium under the condition that the data of that recording medium is erased (or invalidated). As described above, the operation of erasing the original data and copying it on another recording medium is called “move”. For example, when a user thinks that video content recorded in an HDD of the video recorder should be stored for a long period of time, the video content can be moved to a portable recording medium such as a DVD. Thus, both the convenience for the user and the prevention of illegal copying in a large amount can be managed.
As a conventional technology for enabling “move”, there is an invalidation apparatus including a sequential invalidation section for sequentially invalidating partial data that is determined to be invalidated among the target data recorded on a recording medium in order to invalidate the original data during a movement (see, for example, 2002-244926, paragraphs [0024]-[0037], FIG. 2).
FIG. 10 is a block diagram showing an example of functions for controlling copying in a conventional video recorder having two recording media.
In a conventional video recorder 3 shown in FIG. 10, video content can be recorded in an HDD 24 and a BD 25a loaded into a BD drive (BDD) 25. Furthermore, in order to control a copying operation on these recording media, the video recorder 3 includes encryption processing sections 131 and 132, a content movement control section 200, and an EEPROM (Electronically Erasable and Programmable Read Only Memory) 22.
The encryption processing sections 131 and 132 encrypt data of video content (hereinafter abbreviated as “content data”) input from a tuner for a television broadcast and an external input terminal and output the data to the HDD 24 and the BDD 25, respectively. Also, the encryption processing sections 131 and 132 decrypt the content data read from the HDD 24 and the content data read from the BD 25a through the BDD 25, respectively, and output the data.
As one piece of information used for the above encryption and decryption, a set ID that is uniquely assigned to each video recorder is recorded in the EEPROM 22 in such a manner that it cannot be rewritten. Also, in an area called a burst cutting area (BCA) in the BD 25a, a disc ID that is uniquely assigned to each BD 25a is recorded in such a manner that it cannot be rewritten.
When the content data is moved from the HDD 24 to the BD 25a, the content movement control section 200 controls that operation in accordance with copy control information attached to the data.
In the video recorder 3, when content data that is input from a tuner or externally is to be recorded in the HDD 24, the encryption processing section 131 encrypts this content data using a key based on the set ID read from the EEPROM and outputs the data to the HDD 24 only when the copy control information attached to the input content data is “copy once”. Also, in the video recorder in which copying from the HDD 24 to the BD 25a is possible, the encryption processing section 131 usually changes the copy control information to “movable” indicating that “move” is permitted, further encrypts this copy control information, and supplies the information to the HDD 24. The HDD 24 stores therein the encrypted content data and the encrypted copy control information.
As described above, as a result of encrypting content data using the set ID and recording it in the HDD 24, it is possible to prevent the content data from being played back illegally with the content data recorded in the HDD 24 being copied as is on another recording medium in bit units (called “bit-by-bit copy”) or with the HDD 24 itself being loaded into another video recorder.
Furthermore, content data that is input from a tuner or externally may also be recorded directly in the BD 25a. In this case, only when the copy control information attached to the content data is “copy once”, the encryption processing section 132 encrypts the content data using a key based on the disc ID read from the BD 25a by the BDD 25, and outputs the data to the BDD 25. At this time, the copy control information is changed to “copy never”, the information is further encrypted, and the information is supplied to the BDD 25. The BDD 25 records the encrypted content data and the encrypted copy control information in the data area of the BD 25a. 
As described above, as a result of encrypting the content data using the disc ID and recording it on the BD 25a, it is possible to prevent the content data recorded in the BD 25a from being copied bit-by-bit and illegally played back.
In FIG. 10, encryption information such that, for example, information “A” is encrypted by the encryption processing sections 131 and 132 is indicated as “e1[A]” and “e2[A]”, respectively.
When the copy control information given to the content data input from a tuner or externally is “copy never”, none of the encryption processing sections 131 and 132 outputs the content data to the HDD 24 and the BDD 25. Also, when the copy control information is “copy free”, encryption of the content data and the copy control information needs not to be performed, and the copy control information to be notified to the HDD 24 and the BDD 25 may be kept as is as “copy free”.
The processing when the content data recorded in the HDD 24 is moved to the BD 25a is as follows. In FIG. 10, the flow of a signal in this case is indicated by a thick dotted-line arrow.
When the encryption processing section 131 receives the content data and the copy control information read from the HDD 24 and confirms that the copy control information is “movable”, the encryption processing section 131 decrypts the content data and the copy control information by using the key based on the set ID read from the EEPROM 22 and outputs the data to the content movement control section 200. The copy control information is also supplied to the content movement control section 200.
When the content movement control section 200 confirms that the input copy control information is “movable”, the content movement control section 200 outputs the content data from the encryption processing section 131 to the encryption processing section 132. Along with this output, the content movement control section 200 causes the associated content data stored in the HDD 24 to be erased.
When the encryption processing section 132 confirms that the input copy control information is “movable”, the encryption processing section 132 encrypts the input content data by using the key based on the disc ID read by the BDD 25, further encrypts the copy control information as “copy never”, and outputs them to the BDD 25, whereby they are recorded on the BD 25a. As a result, “move” is performed among the different recording media, and the convenience for a user can be increased while protecting the copyright of the content data.
As an HDD installed in the video recorder, it is considered that a product having a general-purpose interface is used. In this case, the HDD in the video recorder can be taken out and relocated to, for example, a personal computer (PC), whereby the HDD is used. For this reason, if the content data encrypted in the manner described above is copied bit-by-bit in a PC environment, an illegal copy product can be produced.
FIG. 11 illustrates, by way of example, illegal copying when an HDD can be relocated to an external PC and can be used.
In FIG. 11, content data encrypted by the above-described method is recorded in the HDD 24 installed in the video recorder 3 (step S1), and this HDD 24 is taken out and is relocated to an external PC 4 (step S2). It is assumed that, for example, another HDD 4a is installed in the PC 4, and in this PC 4, all the data recorded in the HDD 24 is copied bit-by-bit in the HDD 4a (step S3). Thereafter, when the HDD 24 is taken out from the PC 4 and is relocated to the video recorder 3 (step S4), the content data can be moved from the HDD 24 to a BD 25a-1 loaded into the video recorder 3 (step S5).
Next, the HDD 24 in which the content data is erased by “move” is relocated again to the PC 4 (step S6), and the data copied in the HDD 4a in step S3 is copied bit-by-bit to the HDD 24 (step S7). Then, after the HDD 24 is returned again to the video recorder 3 (step S8), by repeating steps S5 to S8, the content data can be recorded on still other BDs 25a-2, 25a-3, . . . .
As described above, in the conventional copyright protection method, there is a problem in that, when the HDD is taken out, the content data is copied bit-by-bit in an external device, and the copied content data is relocated again to the original HDD, illegal copying on a plurality of recording media becomes possible even with content data in which only one copying is permitted.